This project deals with a study of the mechanism of regulation of prostaglandin biosynthesis with special reference to the enzymes responsible for the transformation of the prostaglandin endoperoxide into PGD, PGE and PGF. Effect of heat stable cofactors in supernatant fraction of various tissues and various artificial cofactors on the conversion of the endoperoxide into prostaglandins will be investigated. Optimum conditions for the release of SRSA from cat paws will be defined. A large scale preparation will be made in attempt to isolate SRSA for chemical characterization. A reinvestigation of the chemical identity of the G-acid from human plasma is already underway.